This invention relates to a new and useful method for manufacturing a catalyst composition comprising a large-pore siliceous crystalline molecular sieve, phosphorus, and a matrix material, the new catalyst composition, and use of the new catalyst composition in accordance herewith as a catalyst component for organic compound, e.g., hydrocarbon compound, conversion.
More particularly, this invention relates to a method for preparing a catalyst composition comprising large-pore siliceous crystals, for example, those having the structure of zeolite Beta, ZSM-12, or ZSM-20, wherein the catalyst composition is manufactured in a special way to impart thereto certain valuable catalytic and physical properties and handling characteristics. This invention also relates to the catalyst itself and the use of the catalyst in organic compound conversion.
Catalysts used in Fluid Catalytic Cracking (FCC) processes should be resistant to mechanical attrition, that is, the formation of fines which are small particles, e.g., less than 20 microns in size. The cycles of cracking and regeneration at high flow rates and temperature, such as in an FCC process, have a tendency to break down the catalyst into smaller particles, called "fines," which have a diameter of up to 20 microns as compared with an average diameter of catalyst particles of about 60-100 microns. In an FCC process, catalyst particles typically range from about 10 to about 200 microns, for example, from about 20 to about 150 microns. Excessive generation of catalyst fines increases the refiner's catalyst cost and can be undesirable from an environmental standpoint. It is desirable to develop a catalyst useful in a FCC process that is resistant to mechanical attrition.
Large-pore siliceous crystalline materials include, for example, zeolites having the structure of Beta, ZSM-12, or ZSM-20. Zeolite Beta and its preparation are taught in U.S. Pat. No. 3,308,069, incorporated entirely herein by reference. ZSM-12 and its preparation are taught in U.S. Pat. No. 3,832,449 and 4,552,739, incorporated entirely herein by reference. ZSM-20 and a method for its preparation are taught in U.S. Pat. No. 3,972,983, incorporated entirely herein by reference.
U.S. Pat. No. 4,642,226 teaches a method for synthesizing crystals having the structure of zeolite Beta from a reaction mixture comprising dibenzyldimethylammonium ions as directing agent, and the crystals synthesized thereby. U.S. Pat. No. 5,164,170 discloses a method for synthesizing large crystal size zeolite Beta from a reaction mixture using a directing agent comprising tetraethylammonium compound and including triethanolamine, and the crystals synthesized thereby.
U.S. Pat. No. 4,391,785 teaches a method for synthesis of zeolite ZSM-12 from a reaction mixture comprising, as a directing agent, a compound selected from the group consisting of dimethylpyridinium halide and dimethyl pyrrolidinium halide.
U.S. Pat. No. 4,112,056 teaches a synthesis method for ZSM-12 from a reaction mixture containing tetraethylammonium ions as directing agent. U.S. Pat. No. 4,452,769 claims a method for synthesizing ZSM-12 from a reaction mixture containing methyltriethylammonium ions as the directing agent. European Patent Application 13,630 claims synthesis of ZSM-12 from a reaction mixture containing a directing agent defined as an organic compound containing nitrogen and comprising "an alkyl or aryl group having between 1 and 7 carbon atoms, at least one of which comprises an ethyl radical." U.S. Pat. No. 4,482,531 teaches synthesis of ZSM-12 with a DABCO-C.sub.n -diquat, n being 4, 5, 6, or 10, directing agent; and U.S. Pat. No. 4,539,193 teaches use of bis(dimethylpiperidinium) trimethylene directing agent for synthesis of ZSM-12.
U.S. Pat. No. 4,021,141 teaches synthesis of the ZSM-12 structure from a reaction mixture comprising hexamethyleneimine directing agent.
The entire contents of the above disclosures are incorporated herein by reference as to synthesis and description of the zeolite Beta and ZSM-12 structures and synthesis.
Cracking catalysts for use in petroleum processing generally consist of a zeolitic component and a matrix. The zeolitic material is generally dispersed in an inorganic oxide-type sol or gel matrix material to which one or more clays are added.
Because of the need for higher octane gasoline, there has been an emphasis on octane-increasing improvements in cracking catalysts. Octane-enhancing zeolitic fluid cracking catalysts have been reviewed recently by Scherzer, Catal. Rev. Sci. Eng., 31 (3), 215-354 (1989). The matrix components described in the article include natural or modified clays and inorganic oxides such as silica, alumina, silica-alumina, and silica-magnesia. Other inorganic oxides described for matrices are TiO.sub.2, ZrO.sub.2, P.sub.2 O.sub.5, and B.sub.2 O.sub.3.
Cracking catalysts comprising a zeolite and a matrix material containing aluminum phosphate have been described, for example, in U.S. Pat. Nos. 4,873,211 and 4,228,036. Such catalysts comprising a zeolite and an inorganic oxide matrix which contains phosphorus-treated alumina particles are described in U.S. Pat. Nos. 4,567,152 and 4,584,091 along with U.S. Pat. No. 5,194,412 and in European Patent Applications 176,150 and 403,141. The treatment of zeolite catalysts with phosphoric acid to provide a phosphorus-containing catalyst is described in U.S. Pat. Nos. 4,839,319 and 4,498,975.
In U.S. Pat. No. 4,430,199, tricresyl or ammonium hydrogen phosphate is impregnated into a cracking catalyst to improve the tolerance toward poisoning metals. In addition, boron may be added as a passivating agent.